1. Field of the Invention
The present invention relates to a method for manufacturing a thin film transistor, and more particularly to a method for manufacturing an oxide thin film transistor and a method for manufacturing a thin film transistor display device.
2. Description of the Related Art
In these days, thin film transistor display devices, such as liquid crystal display devices, electrophoretic display devices and organic light emitting diode display devices, have been used more and more widely. To improve display quality of the display devices, people have always paid attention to research and development of structure and manufacturing method of a thin film transistor (TFT) that is one of core structure of the display device.
A conventional thin film transistor has an active layer made of amorphous silicon (a-Si). However, the conventional thin film transistor has some shortcomings, such as high leakage currents, low electron mobility and some of functions of integrated circuit incapable of forming on a substrate directly. Therefore, the conventional thin film transistor fails to satisfy the needs of high display quality of the display devices. For solving the above problems, low temperature polysilicon (LTPS) can be used to make the active layer. However, the process of making the low temperature polysilicon is complicated and has a low product yield, thus the low temperature polysilicon is still not easily to be used widely. Recently, an oxide thin film transistor appears, which has an active layer made of an oxide semiconductor, and can overcomes the above mentioned problems.
However, it is a new application that the oxide semiconductor is used for the active layer of the oxide thin film transistor. Therefore, some topics, such as, how to manufacture the oxide thin film transistor with good performances, are still in research stages.
What is needed, therefore, is a new method for manufacturing an oxide thin film transistor and a new method for manufacturing a display device that can overcome the above-mentioned shortcomings.